1. Field of the Invention
The present invention relates to a disc drive having a motor-driven turntable.
2. Description of the Prior Art
In general, a disc is used as a recording medium for recording information on, and reproducing information from, spiral or concentric tracks thereof. The information recorded on the disc is reproduced by pick-up feeding means including a motor and a plurality of gear trains which are driven and rotated by the motor, and an optical pick-up device which is linearly moved by the pick-up feeding means in a radial direction of the disc.
The disc is rotated by a disc drive when the optical pick-up device is moved. Referring to FIGS. 1 and 2, a conventional disc drive includes a deck base 10, a spindle motor 12 which is installed on the upper surface of the deck base and has a rotary shaft 12a which is engaged with the disc D to rotate the disc D, a turn table 14 on which the disc D is positioned such that non-magnetized portions thereof make contact with the turn table 14, and a clamp (not shown) which is engaged with non-magnetized portions of the disc D positioned on the upper surface of the turn table 14 to prevent deviation of the disc D.
A bracket (not shown) installed at the lower outer peripheral portion of the spindle motor 12 helps to apply current to the spindle motor 12. Two guide members (not shown) are fixed in parallel to each other under the spindle motor 12 and guide the optical pick-up device when the optical pick-up device is moved by the pick-up feeding means.
The spindle motor 12 is press-fitted and installed in the deck base 10, and then the turn table 14 is installed at the upper portion of the rotary shaft 12a of the spindle motor 12 such that it is coaxial to the rotary shaft 12a of the spindle motor 12. The disc is positioned on the turn table 14 and is rotated when current is applied to the spindle motor 12.
The optical pick-up device records and reproduces information on and from the rotating disc when it moves under the disc, and is guided by the parallel guide members.
In the above-mentioned conventional disc drive, however, in case the turn table is tilted, that is, the turn table is not coaxial to the rotary shaft of the spindle motor, then the horizontality of the disc cannot be accurately maintained. As a result, the disc is shaken and deviated during the rotation thereof, and laser beams cannot be projected to desired recording pits of the disc.